1. Field of the Invention
This invention relates generally to faceted gemstone construction and, specifically, to the faceted construction of a brilliant-cut diamond to provide improved luster and appearance.
2. Description of the Related Art
Because the present invention is primarily concerned with a brilliant-cut diamond (although the present invention may be applied to other gemstones), the discussion that follows will focus on brilliant-cut diamonds. The round brilliant cut sets the standard for all other diamond shapes, and accounts for more than 75% of diamonds sold today.
As shown in the prior art diamond profile of FIG. 1, there are three basic sections to a brilliant-cut diamond: the crown 110, the girdle 120, and the pavilion 130. The girdle 120 is the narrow rim of the gemstone that separates the crown 110 from the pavilion 130. It is the section with the largest diameter of any part of the stone. Usually it is left in an unpolished state with a matte finish. However, to achieve more overall brilliance (described below), girdle 120 is often ground. Crown 110 and pavilion 130 can be understood as the xe2x80x9ctopxe2x80x9d and xe2x80x9cbottomxe2x80x9d, respectively, of the brilliant-cut diamond. The tiny facet on the pointed bottom of pavilion 130 is the culet 135. The large, flat top facet of crown 110 is the table 115.
For a cut diamond, a feature of primary importance is its brilliance, which is essentially how much it shines. A diamond has a refractive index of 2.42, which is a very high value compared with that of other jewels (the index of crystal is 1.55; rubies and sapphires, 1.77). As a result, when rays of light incident on table 115 reach pavilion 130, most of the rays are reflected totally (i.e., the rays of light do not escape the diamond through pavilion 130, but are reflected inward again), and escape upon reaching crown 110, thereby reaching the observer""s eyes as brilliance. The angle 137 of pavilion 130 is important to total reflection, and thusly is important to the brilliance of a diamond.
The refractive index of the diamond also gives rise to the dispersion of the totally reflected rays of light into the seven colors of the visible light spectrum. This rainbow effect is sometimes called the fire of the stone. Scintillation is the glittering of the reflected light of a diamond caused by the movement of either the observer or the diamond itself. Scintillation depends primarily on the size of the diamond, the number of facets, the polish of the facets, and the accuracy of the angles of the respective facets.
Diamonds are commonly assessed in terms of the xe2x80x9c4 Csxe2x80x9d: Cut, Clarity, Color, and Carat. Cut refers to both the geometric proportions of a gemstone and the final form into which the rough stone is shaped. The most prominent cuts in the industry are the round brilliant, oval, marquise, pear, heart, emerald, princess, trilliant, and radiant. A good cut gives a diamond its brilliance, dispersion, and scintillation, in short, its appearance and appeal. Clarity is the measure by which a diamond is graded for purity, or whiteness. This is done by taking in the presence or absence of blemishes on the diamond""s surface, or inclusions within the diamond. The professional grading scale is: flawless (F); internally flawless (IF); very, very slightly included (VV); very slightly included (VS); slightly included (SI); imperfect (I).
Color refers to the system of grading diamonds on the quality of their tint, from colorless to a pronounced yellow hue. Modern methods use letters to designate differences in colors. They are D-F, for colorless; G-J, for nearly colorless; K-M, for faintly yellow; N-R, for very light yellow; S-X, for light yellow; Y-Z, for yellow. The traditional method ascribes names to the variations in tint: pure white (extra river; river), top-white (wesselton), off-white (silver cape, tope cape, cape, dark cape), yellow, and brown. Carat is the unit of weight (equal to 200 milligrams) by which a diamond or other gemstone is measured. The word is derived from the carob bean, whose consistent weight was historically used to measure gemstones.
The present invention is primarily directed to the brilliant-cut diamond. The round brilliant-cut diamond is characterized by many facets of different shapes and sizes. This maximizes a diamond""s brilliance by minimizing the amount of light that can escape through pavilion 130, as well as maximizing the scintillation effect of the crown by increasing and varying the reflective surfaces. The typical brilliant cut has 58 total facets and may fit the xe2x80x9cIdeal Cutxe2x80x9d, a range of proportions and angles that are maintained as a standard by the American Gem Society.
The origin of the number of facets (i.e., 58) found in a typical brilliant-cut diamond, and of the xe2x80x9cIdeal Cutxe2x80x9d standard may be found in the history of gemstone cutting. The art of cutting and polishing gemstones is very old, but a unified science and theory of facet proportion is relatively recent. Before the 1900""s, the predecessors of the round brilliant-cut diamond, such as the European or Old Mine cut, varied widely in appearance. Because of the limitations of technology, these diamonds had very small tables, large culets, and short pavilion facets; but there was no single widely-recognized or agreed-upon standard of cutting them.
In 1919, diamond cutter Marcel Tolkowsky wrote a doctoral dissertation that essentially established the modern standard of a brilliant-cut diamond. Using only his own visual assessments of different variations of diamond cuts, Tolkowsky posited a theory of what cutting angles would produce the most proportionate balance of brilliance, scintillation, and dispersion in a gem-quality diamond. His measurements for achieving this balance were exact and strict. Fortuitously, improved cutting techniques and technology were being developed at the same time that finally allowed cutters to achieve more precise and stream-lined designs. Since that time, Tolkowsky""s measurements have evolved into the looser xe2x80x9cIdeal Cutxe2x80x9d standard promulgated by the American Gem Society (AGS).
However, over time, other diamond cutters have found ways to increase the brilliance of the brilliant-cut diamond by exceeding the typical 58 facets. For example, Huisman et al. (U.S. Pat. No. 3,286,486) took the xe2x80x9cconventional twenty-four facetsxe2x80x9d of the brilliant-cut diamond and tripled them to create a pavilion with seventy-two facets. The greatly increased number of facets in the pavilion and the different angles at which a great many of them are cut result in enhanced brilliance. Nevertheless, Huisman et al. left the girdle and crown to be xe2x80x9cof any conventional sizexe2x80x9d. A later patent by the same inventors increased the number of facets of the girdle (Huisman et al. (U.S. Pat. No. 3,585,764)).
Other diamond cutters concentrated on other features besides brilliance. For example, Freiesleben (U.S. Pat. No. 5,657,647) reduces the number of crown facets in order to create large planar surfaces on the top of the diamond in order to xe2x80x9ccreate an impression of calm and hardnessxe2x80x9d. One diamond cutter sought to create greater dispersion (and the capability of highlighting colors) by etching fine grooves (0.1 xcexcm to 1,000 xcexcm) into the planar surfaces of the facets (Nakama (U.S. Pat. No. 5,612,102)). Another diamond cutter sought greater scintillation by making the number of mid-level pavilion facets an odd number rather than the standard even number of facets (Elbe (U.S. Pat. No. 3,788,097).
Although these attempts have met with varying degrees of success, there is always the need for a new brilliant cut which uniquely maximizes and balances the features of brilliance, dispersion, and scintillation of a diamond. Furthermore, there is the need for a brilliant cut with an increased number of facets (in comparison to the typical brilliant cut) in order to increase the brilliance, dispersion, and scintillation of the diamond.
One object of the present invention is to provide a new and unique brilliant cut gemstone which maximizes and balances the features of brilliance, dispersion, and scintillation of a gemstone.
Another object of the present invention is to provide a brilliant cut gemstone with an increased number of facets (in comparison to the typical brilliant cut) in order to increase the brilliance, dispersion, and scintillation of the gemstone.
These and other objects are achieved by a brilliant-cut gemstone according to the present invention. The novel brilliant-cut gemstone comprises a crown, a girdle, and a pavilion. The pavilion has 56 facets. These 56 pavilion facets comprise 8 lower substantially diamond-shaped pavilion facets, 16 middle substantially kite-shaped pavilion facets, and 32 upper substantially triangular shaped pavilion facets.
In one aspect of the invention, the brilliant-cut gemstone has 114 facets. In this aspect, the crown comprises 16 lower triangular crown facets, 16 lower rhomboidal crown facets, 8 middle kite-shaped crown facets, and 16 upper triangular crown facets.
In another aspect of the invention, the brilliant-cut gemstone has 122 facets. In this aspect, the crown comprises 16 lower triangular crown facets, 16 lower rhomboidal crown facets, 8 middle triangular crown facets, 8 first upper triangular crown facets, and 16 second upper triangular crown facets.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.